METHOD FOR DISPENSING LIQUID FROM A MULTI-DOSE CARTRIDGE

Abstract: A method for accessing and dispensing liquid from a multi-dose cartridge of the type having a vent/draw system is disclosed. The method employs using a cartridge interface system having a needle for accessing the cartridge. The needle is attached to a piston, which is in turn connected by means of a crank and linkage to a gear motor. This gear motor drives the piston, effecting the motion of the needle. The action of the gear motor is responsive to signals from various sensors, which permit a fully automated method of accessing and dispensing liquid. In the method, the cartridge is accessed when its presence is detected by the cartridge interface method. Liquid is dispensed continuously until the absence of liquid is detected, at which time the cartride is disabled by disengaging the vent/draw system and disconnecting the cartridge interface system from the cartridge.

Description: ethod for dispensing liquid from a multi-dose cartridge. BACKGROUND OF THE INVENTION Cross Reference to Related Applications This application is a continuation-in-part of application Serial No. 07/850,645, filed March 13, 1992. Field of the Invention The present invention is directed generally to containers and more particularly to single or multi- dose vented containers used to ship liquids requiring ventilation. Description of the Invention Background In certain types of precision equipment, the liquid dispensed into the equipment must be of high quality and/or precise quantity. To achieve those goals, manufacturers often provide cartridges or containers containing liquid of the desired quality and quantity. However, containers or cartridges which can be refilled by the user are susceptible of being refilled with improper quality or imprecise quantities of liquids. For example, in some hydrogen peroxide sterilization systems, it is necessary to use hydrogen peroxide within a limited concentration range. A more concentrated solution of hydrogen peroxide can be hazardous and a less concentrated solution might be ineffective to achieve sterilization under the conditions present in the particular sterilization system. A technician, unaware of the importance of using a particular type of hydrogen peroxide or other liquid, might refill a liquid container with the incorrect type or volume of liquid. In addition, continuous reuse of containers tends to contaminate the container. Hydrogen peroxide solutions will degrade into water and oxygen in the presence of certain contaminants resulting in a less concentrated solution which may be ineffective for its intended use. Moreover, if the container is sealed, the buildup of oxygen upon liquid degradation will pressurize the container, perhaps causing the container to burst. In U.S. patent No. 4,941,519 entitled "Liquid Feed System Using A Non-reusable Container" issued July 17, 1990, a solution is provided to the aforementioned problems. Disclosed in that patent is a non-reusable container used in conjunction with a connection member and a cam member. Operation of the cam member forces the connection member downward into fluid communication with the container. Thereafter, fluid can be removed from the container via a dip tube which extends nearly to the bottom of the container. After all of the fluid has been removed, the cam member is again actuated which causes the vent tube/dip tube to be pushed down dislodging it from the cartridge cap rendering the container non-reusable. With the dip tube thus forced into a position in which it can no longer be used to withdraw liquid from the container, the container is not suited to be refilled and reused. Another example of a sterilant concentration injection system is disclosed in U.S. Patent No. 5,037,623. The apparatus disclosed in that patent provides an arm/needle configuration which punctures a single-dose cartridge. The cartridge is comprised of a vent passage defining a vent aperture at a first end which is in fluid communication with the exterior of the cartridge. The vent aperture is disposed centrally in three dimensions in the interior volume such that when fluid partially fills the interior volume, the vent aperture remains in the head space of the fluid regardless of the orientation of the cartridge. Although the cartridge of U.S. Patent No. 5,037,623 is vented in all orientations of the cartridge, the cartridge is used in a system in which liquid flows through the cartridge. For other types of systems in which the liquid within the cartridge is withdrawn from the cartridge, the thus-spent cartridge requires special handling because of potential residuals left in the cartridge. The invention of U.S. Serial No. 07/850,645, discloses a vented cartridge comprised of a container having a top surface, a bottom surface, and side surfaces connected together to define a predetermined volume. A dip tube extends from the top surface substantially to the bottom surface. A vent tube extends from the top surface and is positioned coaxially with the dip tube. The vent tube has an upper opening positioned in the upper third of the predetermined volume and a lower opening positioned in the lower third of the predetermined volume. A space between an outer surface of the dip tube and an inner surface of the vent tube forms a central fluid communication path between the upper and lower openings and the top surface. An upper valve is positioned at the upper opening for closing the upper opening if the cartridge is oriented with the top surface facing down; a lower valve is positioned at the lower opening for closing the lower opening if the cartridge is oriented with the top surface facing up. This vented cartridge is intended to be used with a liquid feed system of the type which allows withdrawal of the fluid in the cartridge. When the cartridge is spent, the liquid feed system pushes the vent tube and dip tube further into the cartridge thereby disconnecting those tubes from the top surface and preventing the cartridge from being reused. A reservoir member is provided which is drained when the vent tube and dip tube are pushed into the cartridge. When the reservoir member's seal is broken, a diluent is released into the cartridge which renders the designed maximum allowable remaining fluid in the cartridge harmless. The vented cartridge provides a multi-dose cartridge which provides the exact quantity and quality of liquid needed for the intended process. After the cartridge has been spent, the cartridge is mechanically disabled so that it is incapable of being refilled and used again. At the same time that the cartridge is being mechanically disabled, any remaining fluid in the cartridge is being diluted to a point where the cartridge may be disposed of in ordinary trash. Finally, the cartridge is vented during shipping no matter what orientation the cartridge may assume. SUMMARY OF THE INVENTION The present invention is directed to an automated method of using the vented cartridge of the copending application in an improved liquid dispensing system. In the operation of the present invention, the liquid feed system mechanically engages the cartridge by way of a "cartridge interface mechanism", a mechanical assembly which includes a piston which moves the needle, the piston being moved by a crank and linkage arrangement connected to a gear motor. As the cartridge is placed into the dispensing system, its presence is detected by a sensor which permits the cartridge interface mechanism to mechanically engage the cartridge, moving the needle into a position which permits the withdrawal of liquid from the cartridge. At such a time when all the liquid is withdrawn from the cartridge, the cartridge interface system disengages from the cartridge, after first disabling the cartridge from further use by pushing the vent tube and dip tube into the cartridge, thus disconnecting them from access to the cartridge interface system. The cartridge cap includes a diluent reservoir which is opened to the cartridge upon disengagement of the vent and dip tubes by the cartridge interface mechanism, the diluent thus diluting the remaining liquid to a level where it can be disposed of in ordinary trash. After disabling the cartridge, the method of the present invention continues by raising the cartridge interface mechanism to a position which permits operator replacement of the cartridge. The positions of the cartridge interface mechanism are controlled by an arrangement of sensors, located at each position, for halting the motion of the mechanism. The present method permits full automation of the liquid dispensing, offering a greater degree of control than had been attainable with previous methods. These, and other advantages and benefits of the present invention, will become apparent from the Description of a Preferred Embodiment hereinbelow. BRIEF DESCRIPTION OF THE DRAWINGS For the present invention to be clearly understood and readily practiced, it will now be described in conjunction with the following figures wherein: FIG. 1 is a cross-sectional view of the vented cartridge of the present invention; FIG. 2 is an exploded view illustrating the components of the vented cartridge of the present invention; FIGS. 3 and 4 illustrate the lid of the vented cartridge; FIGS. 5 and 6 illustrate the reservoir member of the vented cartridge; FIG. 7 illustrates the vent tube/dip tube assembly of the vented cartridge; FIG. 8 illustrates the dip tube of the vented cartridge; FIGS. 9 and 10 illustrate the upper vent tube portion; FIG. 11 illustrates the lower vent tube portion; FIGS. 12 and 13 illustrate the upper and lower vent guard of the vented cartridge; FIG. 14 is a cross-sectional view as used with the vented cartridge of the present invention; FIGS. 15A and 15B are respective front and side sectional views of the cartridge interface mechanism used with the present invention; FIG. 16 illustrates the vented cartridge; and cartridge interface system in the pre-operative position; FIG. 17 illustrates the vented cartridge and cartridge interface mechanism in mechanical engagement; and FIG. 18 illustrates the cartridge interface system disengaging vent tube/dip tube assembly of the vented cartridge from mechanical contact with the cartridge cap. DESCRIPTION OF A PREFERRED EMBODIMENT Fig. 1 illustrates a vented cartridge 10 of the type disclosed and claimed in the aforementioned U.S. Serial No. 07/850,645. The vented cartridge 10 can be broken down into three functional components: a container 12 which defines a predetermined volume for carrying hydrogen peroxide or any other liquid of interest; a cartridge cap 13 which incorporates a reservoir member 14 for carrying a diluent appropriate for the liquid carried by container 12; and a vent tube/dip tube assembly 16 which provides the means for venting the cartridge 10 as well as withdrawing the liquid from the container 12. The vented cartridge 10 is intended to be used in conjunction with a liquid dispensing system as shown in Figs. 15A and 15B. This liquid dispensing system includes a housing which further includes a top portion in which a cartridge interface mechanism is positioned, and a bottom portion having an opening for receiving the vented cartridge 10 of the present invention. As shown in Figs. 16 and 17, a needle 220 carried by the cartridge interface mechanism, is moved into a first position for sealingly engaging the vent tube/dip tube assembly 16 of the vented cartridge 10 to an inlet port of the liquid feed system. As shown in Fig. 17, the cartridge interface mechanism thereafter assumes a second position wherein the vent tube/dip tube assembly 16 is rendered inoperative and, simultaneously, causes the release of the diluent from reservoir member 14. The diluent dilutes the designed maximum allowable remaining liquid in the cartridge thereby enabling the cartridge to be disposed of with other office trash. The cartridge interface mechanism returns to the position of Fig. 3 which allows the vented cartridge 10 to be removed and replaced with another vented cartridge 10 having a fresh supply of liquid. The present invention is directed primarily to the vented cartridge 10. Turning now to a description of the first major component, the container 12, of the vented cartridge 10, the container 12 is seen in FIG. 2 to be comprised of a jar or bottle shaped member 18 and an appropriately sized lid 20. The container 12 is thus seen as having a top surface 24 provided by the lid 20, a bottom surface 25 which is the bottom of bottle shaped member 18, and a side surface 27 which, in the case of bottle shaped member 18, is cylindrical in shape. The lid 20 carries threads 22 which mate with threads 23 carried by the bottle shaped member 18. In a conventional manner, lid 20 is screwed onto the bottle shaped member 18. When the lid 20 is screwed onto the bottle shaped member 18, the top surface 24 combines with the side surface 27 and bottom surface 25 to define a predetermined volume 29 which the container 12 can hold. In an alternative embodiment, the bottle shaped member 18 may be in the shape of a rectangular parallelpiped. Rather than including threads, the lid 20 and the bottle shaped member 18 may include projecting lips which permit the lid 20 to snap onto the bottle shaped member 18. The lid 20 is shown in greater detail in FIG. 3, which is a view looking downward on top of the lid, and in FIG. 4, which is a cross-sectional view taken along the lines IV - IV in FIG. 3. In FIG. 3, the lid 20 is provided with a plurality of reinforcing ribs 31. An annular space 35 receives an annular sealing member 39, seen in FIG. 1. The annular sealing member 39 may be retained in the annular space 35 by the diluent reservoir member 14 that is snapped into place using retaining bead 41. The function of the annular sealing member 39 will be described in detail hereinbelow. Also illustrated in FIG. 4 is an annular projection 43 formed in the underside of the lid 20. The annular projection 43 defines a circular opening 45. The circular opening 45 may be divided into three portions, an outer annular area 47 extending between annular projection 43 and a cylindrical wall 80, an inner annular area 48 extending between cylindrical wall 80 and a second cylindrical wall 84, and a central circular area 49 defined by the second cylindrical wall 84. As best seen in FIG. 1, inner annular area 48 and central circular area 49 are sized to receive the upper end of the vent tube/dip tube assembly 16. Lid 20 contains four apertures 51 located in annular area 48. The purpose of apertures 51 will become clear after the vent tube/dip tube assembly 16 has been described. Completing the description of the lid 20, the second cylindrical wall 84 defines a bore 53 which is sealed from atmospheric pressure by an extremely thin and frangible portion 55 of the lid 20. The bore 53 carries a detente 56 which is used to mechanically hold the vent tube/dip tube assembly 16 together with the lid 20 as will be described more fully hereinbelow. The reservoir member 14 is shown in greater detail in FIG. 5, which is a view looking upward into the reservoir member 14, and in FIG. 6, which is a cross-sectional view taken along the lines VI-VI in FIG. 5. The reservoir member 14 contains a plurality of radially extending reinforcing ribs 57. The reservoir member 14, as seen in FIG. 6, is substantially cylindrical in shape and is characterized by having an outwardly extending lip 59, an open top, and a closed bottom having a central bore 61. Turning to FIG. 1, it is seen that the central bore 61 is sized to allow the reservoir member 14 to rest upon, and firmly engage, a conical surface of the vent tube/dip tube assembly 16. An 0-ring 63 or other type of sealing member may be provided in the area in which the reservoir member 14 abuts the vent tube/dip tube assembly 16 so as to ensure that the diluent carried in the reservoir 14 does not leak. Remaining with FIG. 1, it is seen that the bottle shaped member 18 carries an inwardly extending lip 65 around its upper periphery. Upon lip 65 is positioned an annular sealing member 67. The outwardly extending lip 59 of the reservoir member 14 is sized to fit on top of annular sealing member 67 as shown in the figure. When lid 22 is screwed on to the top of the bottle shaped member 18, annular sealing member 39 is brought into engagement with outwardly extending lip 59. By applying torque to lid 20, annular sealing members 39 and 67 are compressed, thereby forming a seal between the bottle shaped member 18 and reservoir member 14, and a seal between reservoir member 14 and lid 20, respectively. In that manner, neither the diluent carried by reservoir member 14 nor the liquid carried by container 12 can leak. As will be described further hereinbelow, the purpose of the reservoir member 14 is to be drained upon removal of all the liquid from the container 12 so that the designed maximum allowable residual liquid in container 12 may be diluted to such an extent that the vented cartridge 10 may be disposed with ordinary office trash. The vent tube/dip tube assembly 16 is shown in detail in FIG. 7. The vent tube/dip tube assembly 16 is comprised of an upper vent tube portion 69 which carries an upper vent guard 70 and an upper movable member 71 and a lower vent tube portion 72 which carries a lower vent guard 73 and a lower movable member 74. A vent tube 76, illustrated in FIG. 8, extends substantially throughout the length of the vent tube/dip tube assembly 16 and extends out the bottom of that assembly as seen in FIG. 1. As mentioned, the vent tube is actually comprised of an upper vent tube portion 69, shown in detail in FIGS. 9 and 10, and a lower vent tube portion 72 illustrated in detail in FIG. 11. Turning first to the upper vent tube portion 69, FIG. 9 is a view looking up into the upper vent tube portion 69 while FIG. 10 is a cross-sectional view taken along the lines X - X in FIG. 9. In FIG. 10, the upper vent tube is comprised essentially of a cylindrical wall 78 which, at its upper end, is sized to provide a friction fit (seen in FIG. 1) with the wall 80 defining the inner annular area 48. The upper end of the upper vent tube portion 69 contains a crown member 82 centrally located within circular wall 78. The crown member 82 is rigidly connected to the circular wall 78 except for four bores 95 seen best in FIG. 9. As seen in FIG. 1, the four bores 95 are in fluid communication with an air space 97 formed by inner annular area 48. The air space 97 is in fluid communication with atmospheric pressure through the apertures 51 in the inner annular area 48 of lid 20. Crown member 82 carries a raised bead 83. The crown member 82 and bead 83 are sized to provide a friction fit within the wall 84 defining central circular area 49 and detente 56, respectively, as best seen in FIG. 1. The lower end of crown member 82 contains a circular opening 86 sized to receive dip tube 76. Finally, crown member 82 has a central bore 88 extending therethrough. When the frangible portion 55 of lid 20 is broken, a fluid communication path to the bottom of the container 12 is established through lid 20, bore 53 defined by wall 84, the central bore 88 of crown member 82, and the dip tube 76. Thus, it is seen that a fluid communication path is established from the top surface 24 to substantially the bottom surface 25. Dip tube 76 may have an angled bottom to enable the maximum amount of fluid to be withdrawn from container 12. Alternatively, or in conjunction therewith, the bottom of container 12 may be sloped as illustrated in phantom in FIG. 1 to facilitate maximum removal of the fluid contained within container 12. Returning to a description of FIG. 10, the circular wall 78 has an outside surface 90 and an inside surface 91. Upper apertures 93 extending through wall 78 from inside surface 91 to outside surface 90 permit fluid communication between the interior volume of upper vent tube portion 69 and the predetermined volume 29 defined by container 12. Upper apertures 93 may be located, for example, so as to be in the upper third of the predetermined volume 29. In FIG. 10, it is seen that the upper vent tube portion 69 carries a skirt member 99 which is configured to provide a surface 101 upon which reservoir member 14 may rest and a groove 103 for retaining the 0-ring 63. The skirt member 99 has at its outer periphery an outwardly extending lip which provides a first shoulder 105 and a detente 107. Formed in the outside surface 90 is a second shoulder 109 and detente 111. The two shoulders 105 and 109 and the two detentes 107 and 111 are used to retain upper vent guard 70 as will be described in greater detail hereinbelow. Finally, the circular wall 78 of upper vent tube portion 69 carries appropriate means t" enable mechanical linkage with lower vent tube portion 72. In the instant embodiment, such mechanical means includes an inwardly extending bead 113 formed on the inside surface 91 of circular wall 78. The reader will understand, however, tnat other types of mechanical means for connecting the upper vent tube portion 69 and lower vent tube portion 72 may be provided. The lower vent tube assembly 72 is illustrated in FIG. 11. The lower vent tube assembly 72 is comprised essentially of a cylindrical wall 115. The upper end of the cylindrical wall 115 has a reduced outside diameter sized to fit inside of the lower end of the upper vent tube portion. A step or shoulder 121 is present where the area of reduced outside diameter begins. Also carried by the outside surface 119 is a detente 123. As seen in FIG. 1, the lower end of upper vent tube portion 59 slides along the area of reduced diameter until it strikes shoulder 121 at which time the bead 113 engages detente 123. In that manner, the upper vent tube portion 69 and lower vent tube portion 72 are mechanically interconnected. The lower vent tube portion 72 carries a circular member 125. The circular member 125 has an outwardly extending lip forming a first shoulder 105, and a corresponding detente 107. Formed in the outer surface of wall 115 is a second shoulder 109 and a corresponding detente 111. First and second shoulders 105 and 109 and first and second detentes 107 and 111, respectively, perform the same functions with respect to the lower vent tube portion 72 as they perform with respect to the upper vent tube portion 69 and therefore have been given the same reference numerals as were given in the description of the upper vent tube portion. Completing the description of the lower vent tube portion 72 illustrated in FIG. 11, wall 117 contains a bead 127 sized to sealingly engage dip tube 76. The cylindrical wall 115 has an inside surface 117 and an outside surface 119. Wall 117 has lower apertures 129 extending therethrough from the inside surface 117 to the outside surface 119 which allow the interior volume of the lower dip tube portion 72 to be in fluid communication with the predetermined volume 29 of the container 12. The apertures 129 may be located, for example, in the lower third of the predetermined volume 29. The final components of the vent tube/dip tube assembly 16 are the upper vent guard 70 and the lower vent guard 73 which are illustrated in detail in FIG. 12, which is a view looking up into vent guard 70, and FIG. 13 which is a cross-sectional view taken along the lines XIII - XIII in FIG. 12. The upper vent guard 70 and lower vent guard 73 are identical in construction and operation such that only one need be described. As seen in FIG. 13, upper vent guard 70 is substantially comprised of a cylindrical wall 131. The cylindrical wall 131 carries a raised bead 133 on its interior surface at one end thereof. At the other end of the cylindrical wall 131, the upper vent guard 70 includes a central ring 135 which is connected to the cylindrical wall 131 through a plurality of ribs 137. Central ring 135 and ribs 137 cooperate to define a plurality of openings 139 seen best in FIG. 12. Ring 135 carries a raised bead 141 along its interior surface. As previously mentioned, the upper vent guard 70 is carried on the upper vent tube portion 69. That is accomplished in the following manner. Referring to FIG. 1, it is seen that the inside diameter of one end of the vent guard 70 is sized to fit over the outside diameter of skirt member 99. When so positioned, a transverse edge 132 of wall 131 butts against shoulder 105 and raised bead 133 engages detente 107. Similarly, a transverse edge 134 of central ring member 135 butts against shoulder 109 and raised bead 141 engages detente 111. In that manner, upper vent guard 70 is fixably carried by upper vent tube portion 69. The upper vent guard 70 is positioned such that cylindrical wall 131 surrounds apertures 93. The reader will understand that lower vent guard 73 is similarly constructed, is likewise fixably carried by lower vent tube portion 72, and is positioned such that cylindrical wall 131 surrounds apertures 129. Upper vent guard 70 has a plurality of C-shaped members 143 extending from the exterior surface of wall 131 at one end thereof. The C-shaped members 143 are used to retain movable members 145 best seen in FIGS. 1 and 2. The movable members 145 are annularly shaped and sized to entirely cover openings 139 when the movable member is adjacent to surface 147 of the vent guard 70. That is referred to as the valve seat position. By virtue of the movable member's 145 annular shape, the movable member is capable of sliding along either the upper vent tube portion 69 or the lower vent tube portion 72, wherever it happens to be located. Movement away from the valve seat position is ultimately restrained by the C-shaped members 143. When the movable member is engaging C-shaped members 143, that position is referred to as the valve stop position. Referring now to FIG. 1, the operation of the cartridge 10 of the present invention will now be described. Prior to transportation, lid 20 is screwed tightly onto bottle-shaped member 18 thereby sealing the liquid within container 12 and the diluent within reservoir 14 when the cartridge 10 is oriented such that the top surface 24 is facing up, the force of gravity acting upon movable member 145 carried on the lower vent tube portion 72 will move member 145 into the valve seat position. As seen from the figure, when the movable member 145 is in the valve seat position, apertures 139 are covered. In that manner, the lower vent guard 73 and movable member 145 form a valve which affectively controls apertures 129. While the cartridge 10 is oriented with the top surface 24 facing up, movable member 145 carried on the upper vent tube portion 69 will be in the valve stop position. In that position, apertures 139 are not covered. Accordingly, as indicated by arrows 147, an upper fluid communication path between upper apertures 93 and the predetermined volume 29 is established. The upper apertures 93 are also in fluid communication with the atmosphere through the following path. The inside surface 91 of the upper vent tube portion 69 and the inside surface 117 of the lower vent tube portion 72 cooperate with the outside surface of the dip tube 76 to form an annular, central, fluid communication path running essentially the entire length of the vent tube/dip tube assembly 16. That fluid communication path then continues through bores 95, airspace 97, and apertures 51 in the inner annular area 48 of lid 20. Thus, when the vented cartridge 10 is so oriented, a vent path between the head space of the liquid and the atmosphere is provided. In the event that the cartridge 10 is oriented so that the top surface 24 is facing down, the function of the upper vent guard 70 and lower vent guard 73 are essentially reversed. That is, in such an up-side-down orientation, movable member 145 carried on upper vent tube portion 69 will, by virtue of gravity, be in the valve seat position. Accordingly, apertures 139 will be covered and apertures 93 will be essentially sealed off from the predetermined volume 29. However, movable member 145 carried on the lower vent tube portion 72 will be in the valve stop position. As such, apertures 139 of the lower vent guard 73 will provide a lower fluid communication path as indicated by broken arrows 149. Thus, apertures 129 will be in fluid communication with the predetermined volume 29 through the lower fluid communication path. Apertures 129 are in fluid communication with the atmosphere through the aforementioned central fluid communication path. Those of ordinary skill in the art will recognize that it is desirable to place hydrophobic membranes 150 at some point in the upper and lower fluid communication paths and/or the central fluid communication path. As shown in FIG. 1, hydrophobic membranes 150 are shown positioned over openings 139 and covering apertures 51. Although it is anticipated that the vented cartridge 10 may be filled with any volume of fluid so long as at least one of the upper and lower fluid communication paths remains in the head space of the fluid, in the preferred embodiment in which hydrogen peroxide is carried by the vented cartridge 10, the hydrogen peroxide level will be below the C-shaped members 143 carried by the lower vent guard 73. In an upright orientation, movable member 145 carried by lower vent tube portion 72 will, by force of gravity, be in the valve seat position such that the hydrophobic membranes 150 of lower vent guard 73 are protected from splashing hydrogen peroxide. At the same time, movable member 145 carried by the upper vent tube portion 69 will be in the valve stop position such that the upper fluid communication path will be open. The vent guards' 70 and 73 construction is the result of the design requirements for their openings 139 to permit the required air transmissibility through the hydrophobic membrane 150 to prevent over pressurization of the bottle. Thus, whether the cartridge is oriented in an upright position or in an up-side-down position, the cartridge 10 will always be capable of being vented. Should the cartridge 10 be oriented on its side, the force of gravity will be insufficient to close off either the upper or the lower fluid communication paths when the cartridge is properly filled. In such an orientation, the level of hydrogen peroxide will be below both the upper and lower fluid communication paths. Through the aforementioned construction, it is seen that the vented cartridge 12 is vented in all orientations during shipment. When the vented cartridge 10 is to be used, a needle 220, shown in FIGS 16-18, punctures the frangible area 55 of the lid 20 and enters the bore 53 defined by wall 84. The frangible surface 55 is forcibly pushed back by entry of the needle 220 such that a seal is formed between the needle and the bore 53 above the frangible surface 55 of lid 20. At that point, the contents of container 12 may be withdrawn by use of a vacuum. The fluid communication paths which are allowed for venting during transportation and storage, are now relied upon to provide air to replace the withdrawn fluid to prevent the cartridge 10 from collapsing. During that function, the hydrophobic membranes 150 filter the ambient incoming air to prevent contamination that could degrade the hydrogen peroxide. After the contents of the container 12 have been withdrawn, the needle 220 is inserted further until it contacts crown member 82. Further insertion of the needle forces the entire vent tube/dip tube assembly 16 out of engagement with lid 20 thus rendering cartridge 10 incapable of being reused. At the same time that the vent tube/dip tube assembly 16 is pushed out of engagement with lid 20, the seal between the reservoir 14 and the vent tube/dip tube assembly 16 is broken thereby allowing the diluent to enter container 12. The present invention employs a cartridge interface mechanism 200 for withdrawing the sterilant. The cartridge interface mechanism 200 is a mechani al assembly which includes a piston 210 that cooperates with the needle 220 that performs the engage function and the ejection of the vent tube/dip tube assembly 16. The piston is powered by a gear motor 230 which controls the needle operation, in the preferred embodiment, by means of a crank and linkage 235. In the cartridge interface mechanism 200, as shown in FIGS. 15A, 15B, 16, 17 and 18, the gear motor 230 drives the piston 210 which varies the needle position in order to engage and disengage the cartridge 10 in an automated fashion. The gear motor is activated and deactivated in response to user input and signals received from optical sensors 201, 202. The gear motor 230, optic sensors 201, 202 and liquid indicator 240 are connected electronically to a computer control system. User input for function commands is made through a control panel keypad. As used with the subject sterilant delivery system, the presence of sterilant available for processing is detected by a liquid indicator 240 located on the mechanical apparatus immediately downstream from the needle 220, providing for immediate detection of an empty container. By monitoring the presence of the sterilant using the liquid indicator 240 and also by using piston position sensors 201, 202, to detect the position of the actuating piston, the gear motor 230 is controlled such that removal of the sterilant cartridge prior to the complete use of sterilant is avoided. This feature prevents undesired exposure of the user to concentrated sterilant and insures that if a constant supply of sterilant to the sterilizer is not being delivered, that the cycle will abort. In the operation of the present method as shown particularly in FiGS. 16-18, the cartridge is placed inside the chamber 250 of the cartridge interface mechanism 200. The door 251 of this chamber 250 is then closed. The cartridge's presence is registered by a chamber switch 260, located on the inside of the chamber 250, which contacts the exterior of the lid 20 when the cartridge 10 is in its proper position, thus indicating proper alignment in the chamber 250. The cartridge 10 is brought into mechanical engagement with the cartridge interface mechanism 200 when the needle 220 comes down and pierces the frangible surface 55 of the lid 20. A new seal is created by the interference fit of the needle 220 into the bore 53. The needle 220 is stopped in the "draw" position by a sensor flag 203 which activates piston position sensor 202, thus stopping piston movement. A path for the supply of sterilant to the sterilizer has now been created. The draw for the sterilant is created by a vacuum supplied by the sterilizer. As the cartridge contents are drawn from the cartridge 10, sterilant will be replaced by air in the cartridge 10 and eventually, as the bottle empties, into the sterilant supply line 241. The liquid indicator 240, located immediately downstream from the needle 220 senses either the presence or absence of liquid sterilant. In the preferred embodiment, the liquid indicator is a capacitance sensor, as are known in the art. When hydrogen peroxide sterilant flows through supply line 241, the higher dielectric constant of the sterilant produces an output from the sensor which indicates the presence of liquid sterilant. When the sterilant supply line 241 is empty of sterilant, the lower dielectric constant from the absence of the sterilent changes the state of the sensor that is eguatal to no sterilant present. This signal charge of the sensor is detected by the computer control system, and indicates an empty cartridge. This condition is communicated to the user via a display screen and an audible alarm. The sterilization cycle is aborted at this point because a sufficient volume of sterilant may not be available in the sterilant tubing to complete a full cycle. Upon completion of withdrawal of the sterilant from the cartridge 10, it is desirable to dilute any residual sterilant remaining in the cartridge 10 to a harmless concentration level, so that it may be disposed with ordinary trash. The signal from the liquid indicator 240 effects the lowering of the piston so that the needle 220 moves downward, pushing the dip tube/vent tube assembly 16 away from the lid 20 thus disengaging the dip tube/vent tube assembly 16 and opening the diluent reservoir 14 into the cartridge cavity. The diluent that was contained in the diluent reservoir 14 will then flow into the cartridge 10 and dilute the residual sterilant. With this same action, the dip tube/vent tube seal is permanently broken, rendering the cartridge 10 unusable. The needle 220 is then withdrawn from the lid 20 to the point where it has resumed its initial position, and is stopped there by the passage of the sensor flag 203 across sensor 201. The used cartridge 10 may now be removed for proper disposal and a new cartridge put in its place to repeat the cycle. While the present invention has been described in conjunction with a preferred embodiment, those of ordinary skill in the art will recognize that many changes and modifications can be made to the preferred embodiment described herein. All such changes and modifications are intended to be covered by the foregoing description and the following claims.

Claims: What is claimed is: 1. An automated method for dispensing a liquid comprising the steps of: a) providing a cartridge containing the liquid to be dispensed; b) placing the cartridge into a dispensing unit and automatically detecting the presence of the cartridge inside the dispensing unit to create a cartridge detection signal; c) establishing a fluid connection between the cartridge and the dispensing unit in response to said cartridge detection signal; d) automatically monitoring and detecting the presence of the liquid to be dispensed to create a liquid detection signal; e) withdrawing a predetermined amount of the liquid from the cartridge using the dispensing unit in response to an indication of sufficient liquid from the liquid detection signal; f) disconnecting the cartridge from the dispensing unit while simultaneously disabling the cartridge from further use in response to an indication of insufficient liquid by the liquid detection signal; and g) removing the cartridge from the dispensing unit. 2. The automated method as recited in claim 1 wherein the step of detecting the cartridge further comprises using an electronic detector to create the cartridge detection signal. 3. The automated method as recited in claim 1 wherein the step of establishing a fluid connection further comprises bringing the cartridge into mechanical engagement with an interface mechanism on the dispensing unit. 4. The automated method as recited in claim 3 wherein the interface mechanism includes a needle which is displaced by a piston, said cartridge includes a lid which is integral with a dip tube/vent tube assembly which extends into the depth of the cartridge, and wherein the step of bringing the cartridge cap into mechanical engagement with the interface mechanism further comprises displacing said needle to engage with the upper end of said lid to create an interference fit which forms a fluid seal, providing a fluid channel with said dip tube/vent assembly. 5. The automated method as recited in claim 4 wherein said interface mechanism includes a gear motor which is mechanically connected to the piston, wherein the gear motor displaces the piston in response to the cartridge detection signal upon indicate of the presence of the cartridge, and the needle is lowered thereby to engage the cartridge lid at a withdrawal position substantially proximate to the draw tube, in order to withdraw the liquid from the cartridge. 6. The automated method as recited in claim 5 wherein the step of disconnecting and disabling the cartridge further comprises lowering the needle to a disconnecting position so that the dip tube/vent tube assembly is broken away from the lid. 7. The automated method as recited in claim 6 wherein the needle is lowered to : " s disconnecting position by said piston in response to the liquid detection signal upon indication of the absence of liquid through a liquid delivery line. 8. The automated method as recited in claim 6 wherein the cartridge cap includes a diluent reservoir, and wherein disconnection of the dip tube/vent tube assembly from the cartridge lid permits the diluent reservoir to release the diluent, which dilutes any liquid remaining in the cartridge. 9. The automated method as recited in claim 6 wherein upon disengaging the dip tube/vent tube assembly, the piston moves the needle upward to a replacement position that permits the replacement of the cartridge. 10. The automated method as recited in claim 1 wherein the liquid is hydrogen peroxide sterilant. 11. The automated method as recited in claim 1 wherein the step of withdrawing the liquid further comprises applying a vacuum to the cartridge from the dispensing unit to withdraw the liquid. 12. The method recited in claim 1 wherein the step of monitoring and detecting the liquid further comprises communicating the absence of sterilant to the dispensing unit operator by displaying a visual warning and triggering an audible alarm. 13. An automated method for delivering hydrogen peroxide into a sterilizer comprising the steps of: a) placing a cartridge for holding the hydrogen peroxide into a receptacle; b) connecting the cartridge to the sterilizer; c) withdrawing the hydrogen peroxide from the cartridge, through a tube connected to the lid, by a needle connected to the sterilizer; d) monitoring for the presence or absence of hydrogen peroxide in the tubing; e) simultaneously diluting the hydrogen peroxide remaining in the cartridge after delivery to the sterilizer and disabling the cartridge from further delivering hydrogen peroxide to the sterilizer; f) disconnecting the cartridge from the sterilizer; and g) removing the cartridge from the holding device or receptacle. 14. The method recited in claim 13 wherein the step of diluting the hydrogen peroxide remaining in the container further comprises releasing diluent from a diluent reservoir, located in the cartridge lid, into contact with the hydrogen peroxide.

Inventors: BUTLER KEVIN H, DIAZ JAIME, LITTLE WILLIAM C, MIELNIK THADDEUS J JR, BUTLER, KEVIN, H., DIAZ, JAIME, LITTLE, WILLIAM, C., MIELNIK, THADDEUS, J., JR.
Applicants: AMERICAN STERILIZER CO, AMERICAN STERILIZER COMPANY
Application year: 1994
Main classification: B67D5
IPC codes: B65D83, B67D1, B67D5